1. Field of the Invention
This invention relates to a method and apparatus for anchoring a tool in an accurate and stable manner in a cased borehole for use in high pressure environments.
2. Description of the Prior Art
Oil and natural gas welling requires drilling a borehole through an earth formation. The borehole must accommodate welling and drilling equipment as well as inflow and outflow of various fluids through the borehole and the surrounding earth formation. Typically, during the preparation and maintenance of an earth formation borehole, steel casing is used in one or more sections of the borehole to stabilize and provide support for the formation surrounding the borehole. Cement is poured on the outside of the casing to support the casing and provide a seal between the formation and the casing.
There are thousands of abandoned oil and gas wells around the United States and many more worldwide. Recent research has indicated that large amounts of unrecovered oil and natural gas may be present in such abandoned wells. Recovering this unrecovered oil and natural gas may be financially attractive because the majority of the field development costs such as drilling, casing and cementing have already been incurred in the abandoned wells.
Various testing equipment exists that perforates the casing and the cement surrounding the borehole in order to test the surrounding formations for additional retrievable resources. This testing equipment must operate in harsh environments, often at great depths and under great pressures.
MacDougall et al., U.S. Pat. No. 5,692,565, discloses one such testing device for sampling an earth formation surrounding a cased borehole. The MacDougall et al. patent teaches a testing device that requires a means for setting the device at a substantially fixed location. The testing device according to the MacDougall et al. patent requires a substantially fixed location so that various drilling and plugging tools may be used during the testing and sampling of the formation surrounding the cased borehole.